program fac;
var f:text;
n,i,j,nr:longint;
phi:array[1..1000000] of int64;
begin
 assign(f,'fractii.in'); reset(f);
 readln(f,n);
 close(f);
 for i:=1 to n do
  phi[i]:=i-1;
  for i:=2 to n do begin
   j:=2*i;
   while j<=n do begin
    phi[j]:=phi[j]-phi[i];
    inc(j,i);
   end;
  end;
 nr:=0;
 for i:=2 to n do
  nr:=nr+phi[i];
 assign(f,'fractii.out'); rewrite(f);
 writeln(f,2*nr+1);
 close(f);
end.